Travis to run benchmarks on HHVM/1000

Running benchmarks for a 1000 page load takes about 8 min to complete on Zend
therefore using HHVM which just takes about 3 min.
Fix 520
Merge pull request #522 from SemanticMediaWiki/travis

Travis to run benchmarks on HHVM/1000
Merge pull request #531 from SemanticMediaWiki/fix-520

Fix #520
Update RELEASE-NOTES.md

[skip ci]
Add value fingerprint hash to eliminate duplicates in query display